1. Field of the Invention
This invention relates to gas generators and is particularly directed to solid propellant gas generators for producing high yields (&gt;50% by weight) of pure nitrogen gas.
2. Description of the Prior Art
Previously developed gas generators for the production of nitrogen gas have employed sodium azide as the primary source of nitrogen in conjunction with a variety of solid oxidizers. Typical oxidizer examples are fluorocarbon polymers such as Viton A (U.S. Pat. No. 3,977,924), Teflon (U.S. Pat. No. 3,833,432), cupric oxide (German Pat. No. 2,327,741) and numerous others.
U.S. Pat. No. 3,947,300 describes a propellant system in which sodium azide is used with the inorganic oxidants (chlorates, nitrates, chromates, and peroxides) in conjunction with flux promoting compounds such as silicon dioxide. A typical example (5:1:2 molar ratio of NaN.sub.3 :NaNO.sub.3 :SiO.sub.2) would result in a 42.2 weight percent yield of nitrogen at a temperature of 2050.degree. K.
All of the previous work has resulted in nitrogen gas yields of 20 to 45 weight percent, and propellant physical properties which are marginal in that small pieces of the pressed grains erode upon vibration of the containing vessel. This often results in erratic pressurization rates upon ignition of the propellant change.
Utilization of flux promoting compounds such as SiO.sub.2 also degrade physical properties, but also increase the flame temperature due to secondary chemical reactions such as: EQU Na.sub.2 O+SiO.sub.2 .fwdarw.Na.sub.2 SiO.sub.3
The additional heat released from the secondary reactions must then be absorbed in a heat transfer media which adds to the complexity of the overall system.